Boat construction



April 8, 1969 c. H. BENNETT 3,437,069

BOAT CONSTRUCTION Filed Oct. 5, 1966 Sheet I of 2 //O 122 /2 MW Ow I I E 2/ i l 1 I /A I l g o 0 o FIG. 2

INVENTOR. Cf/flAA 4-1: H. fiat/M577- A r romyzrs April 8, 1969 c. H. BENNETT 3,437,069

BOAT CONSTRUCTION .Jiled Oct. 5, 1966 Sheet 2 or 2 FIG.5

INVENTOR. ovnkz 3 8511/4/57 am, 64% mfa' a A T TORNEVS United States Patent 3,437,069 BOAT CONSTRUCTION Charles H. Bennett, 14845 Plymouth Road,

Detroit, Mich. 48227 I Filed Oct. 5, 1966, Ser. No. 584,428 Int. Cl. B63h /06, 21/26 US. Cl. 115-34 2 Claims ABSTRACT OF THE DISCLOSURE This invention relates to boat construction and is applicable to inboard boats, outboard boats and inboardoutboard boats.

Among the objects of the invention are to provide a propeller arrangement which operates at greater efliciency; and to provide a combined propeller, strut and exhaust arrangement wherein a more efficient operation of the boat and engine is achieved, noise is substantially reduced, and the need for an expensive mufller is substantially eliminated, steam in the exhaust fumes is buried in the water, fumes emanating from the exhaust pipe are buried in the water and the passage of fumes upwardly to the passengers of the boat is substantially eliminated.

In the drawings:

FIG. 1 is a fragmentary side elevational view of a boat embodying the invention.

FIG. 2 is a fragmentary sectional view on an enlarged scale taken along the line 2-2 in FIG. -1.

FIG. 3 is a fragmentary side elevational view of a further modified form of boat construction.

FIG. 4 is a fragmentary sectional view taken along the line 4-4 in FIG. 3 parts being broken away.

FIG. 5 is a sectional view taken along the line 5-5 in FIG. 3 parts being broken away.

FIG. 6 is a fragmentary view taken along the line 66 in FIG. 4 parts being broken away.

Referring to FIG. 1, the boat 10 comprises a bottom 11 and rear transom 12. A conventional inboard engine, E, is mounted in the boat and includes a drive shaft 13 that extends downwardly and rearwardly beneath the bottom 11 of the boat 10.

In accordance with the invention, a mounting plate 14 and strut 15 are fixed to the bottom of the boat 11 by bolts 16. A propeller 17 is fixed to the shaft 13 and journalled to the lower end of the strut 15 in a position forwardly of the strut 15 and in close proximity thereto. The hub 18 of the journal is preferably frusto-conical and diverges rearwardly to its greatest size at the trailing edge to define spaced rear edges.

As shown in FIG. 2, the strut 15 has tapered sides 20 that extend outwardly and rearwardly to spaced rear edges that produce a cavitation area A adjacent the rear of the strut. The engine exhaust tube 21 extends downwardly through the bottom 11 of the boat in close proximity to the cavitation area A so that the exhaust gases are drawn downwardly into the water. In order to increase the size of the cavitation area A, a hollow vertical space 22 is preferably provided along the trailing edge of the strut 15. In order to minimize propeller cavitation, the bottom 23 of the plate 14 is tapered downwardly and rearwardly.

Further in the case of single or plural propellers rotating in the opposite direction, the strut 15 is preferably positioned unsymmetrically with respect to the axis of the propeller shaft 13, as shown in FIG. 2, in order that the impingement of the screw current on the strut 15 will be reduced. Thus, if the propeller is rotating clockwise as viewed from the rear of the boat, the strut is positioned so that the plane of the strut extends forwardly and to the left with respect to the axis of the propeller shaft. If the propeller is rotating counterclockwise as viewed from the rear of the boat, the plane of the strut extends forwardly and to the right with respect to the axis of the propeller shaft.

The invention can also be applied to an outboard motor as shown in FIGS. 3-6 wherein the strut 30 forms part of the outboard motor and encloses the conventional shaft that transmits the force downwardly to the propeller. As shown, the strut is tapered rearwardly to form a cavitation area A (FIG. 5). The gearing is shown diagrammatically in the drawings. The propeller 3-1 is mounted forwardly but in close proximity to the strut 30 and the engine exhaust passage 32, forming part of the outboard engine, is directed downwardly toward the cavitation area A. In order to enhance the cavitation area, a groove 33 extends downwardly along the rear or trailing edge of the strut 30. An anti-cavitation plate 35 is provided on the boat in overlying relation to the propeller.

In each of the forms of the invention, the provision of the strut rearwardly of the propeller permits a reduction in frontal area and size of the portion of the strut which supports the propeller and acts as a pilot bearing. This strut barrel portion can be made conical in shape to take advantage of the natural centrifugal action of the screw current as it leaves the propeller. This will form what is in effect an inverted venturi with the water surrounding the screw current forming a barrier or outer confining surface and as a result the velocity of the screw current will increase therefore resulting in increased speed of the boat. It is preferred that all portions of the mounting section of the strut taper uniformly from the rear toward the front of the strut. Further, the axis of the supporting section of the strut barrel is preferably parallel to the bottom of tfltie boat and at an angle to the axis of the propeller sha The provision of a plate overlying the propeller not only minimizes propeller cavitation but, in addition, permits the propeller to be mounted more closely to the bottom of the boat, the plate taking up wear that may occur because of the movement of the water relative to the bottom of the boat.

In each of the forms of the invention, as the exhaust gases move toward the cavitation area at the rear of the strut, they encounter the movement of the propeller screw current rearwardly causing the exhaust gases including steam to be buried in the water. Further, the noise of the gases is also absorbed in the water. An additional advantage is that the exhaust gases are drawn downwardly from the exhaust pipe to produce a greater suction elimi nating back pressure improving the efficiency of the engine. Obviously, the passage of exhaust gases including the odor and the poisonous constituents of the gases toward the passengers is eliminated.

It can thus be seen that the invention is applicable to inboard boats, outboard boats and can also be applied to inboard-outboard boats.

I claim:

1. In a boat construction, the combination comprising a boat,

an engine mounted on the boat,

a strut extending downwardly below the waterline,

a propeller,

means for mounting the propeller on the strut in a position forwardly of the strut and in close proximity thereto,

said strut having a horizontal cross section which terminates in spaced edges at the rear in the area from the water level downwardly to form a cavitation area adjacent the trailing edge of the strut,

the horizontal cross section of said strut being unsymmetrically displaced horizontally with respect to the axis of the propeller.

2. In a boat construction, the combination comprising a boat,

an outboard engine mounted on the boat,

a strut extending downwardly from the engine below the waterline,

said strut forming part of the outboard engine,

a propeller mounted on the strut in a position forwardly of the strut and driven by drive means within the strut,

the horizontal cross section of said strut being unsymmetrically displaced horizontally with respect to the axis of the propeller,

said strut having a horizontal cross section which terminates in spaced edges at the rear in the area from the water level downwardly to form a cavitation area adjacent the trailing edge of the strut,

said engine having an exhaust terminating closely adjacent to the trailing edge of the strut and being directed generally toward said cavitation area.

References Cited UNITED STATES PATENTS 1,714,042 5/1929 Oertz 114162 2,905,131 9/1959 Costa 11534 3,092,185 6/1963 Alexander 11517 X 3,109,495 11/1963 Lang. 3,306,246 2/1967 Reder. 1,744,138 1/1930 Oertz 114162 TRYGVE M. BLIX, Primary Examiner.

US. Cl. X.R. 

